package com.merelyb.util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

/**
 * Created by liming on 2016/5/23.
 * 获取农历日期
 */
public class GregorianToLunar {
    private  String chineseNumber[] = {"一", "二", "三", "四", "五", "六", "七", "八", "九", "十", "十一", "十二"};
    private  SimpleDateFormat chineseDateFormat = new SimpleDateFormat("yyyyMMdd");
    private long[] lunarInfo = new long[]
            {0x04bd8, 0x04ae0, 0x0a570, 0x054d5, 0x0d260, 0x0d950, 0x16554, 0x056a0, 0x09ad0, 0x055d2,
                    0x04ae0, 0x0a5b6, 0x0a4d0, 0x0d250, 0x1d255, 0x0b540, 0x0d6a0, 0x0ada2, 0x095b0, 0x14977,
                    0x04970, 0x0a4b0, 0x0b4b5, 0x06a50, 0x06d40, 0x1ab54, 0x02b60, 0x09570, 0x052f2, 0x04970,
                    0x06566, 0x0d4a0, 0x0ea50, 0x06e95, 0x05ad0, 0x02b60, 0x186e3, 0x092e0, 0x1c8d7, 0x0c950,
                    0x0d4a0, 0x1d8a6, 0x0b550, 0x056a0, 0x1a5b4, 0x025d0, 0x092d0, 0x0d2b2, 0x0a950, 0x0b557,
                    0x06ca0, 0x0b550, 0x15355, 0x04da0, 0x0a5d0, 0x14573, 0x052d0, 0x0a9a8, 0x0e950, 0x06aa0,
                    0x0aea6, 0x0ab50, 0x04b60, 0x0aae4, 0x0a570, 0x05260, 0x0f263, 0x0d950, 0x05b57, 0x056a0,
                    0x096d0, 0x04dd5, 0x04ad0, 0x0a4d0, 0x0d4d4, 0x0d250, 0x0d558, 0x0b540, 0x0b5a0, 0x195a6,
                    0x095b0, 0x049b0, 0x0a974, 0x0a4b0, 0x0b27a, 0x06a50, 0x06d40, 0x0af46, 0x0ab60, 0x09570,
                    0x04af5, 0x04970, 0x064b0, 0x074a3, 0x0ea50, 0x06b58, 0x055c0, 0x0ab60, 0x096d5, 0x092e0,
                    0x0c960, 0x0d954, 0x0d4a0, 0x0da50, 0x07552, 0x056a0, 0x0abb7, 0x025d0, 0x092d0, 0x0cab5,
                    0x0a950, 0x0b4a0, 0x0baa4, 0x0ad50, 0x055d9, 0x04ba0, 0x0a5b0, 0x15176, 0x052b0, 0x0a930,
                    0x07954, 0x06aa0, 0x0ad50, 0x05b52, 0x04b60, 0x0a6e6, 0x0a4e0, 0x0d260, 0x0ea65, 0x0d530,
                    0x05aa0, 0x076a3, 0x096d0, 0x04bd7, 0x04ad0, 0x0a4d0, 0x1d0b6, 0x0d250, 0x0d520, 0x0dd45,
                    0x0b5a0, 0x056d0, 0x055b2, 0x049b0, 0x0a577, 0x0a4b0, 0x0aa50, 0x1b255, 0x06d20, 0x0ada0};

    /**
     * 传回农历 y年的总天数
     * @param iYear
     * @return
     */
    private int yearDays(int iYear) {
        int i, sum = 348;
        for (i = 0x8000; i > 0x8; i >>= 1) {
            if ((lunarInfo[iYear - 1900] & i) != 0) sum += 1;
        }
        return (sum + leapDays(iYear));
    }

    /**
     * 传回农历 y年闰月的天数
     * @param iYear
     * @return
     */
    private int leapDays(int iYear) {
        if (leapMonth(iYear) != 0) {
            if ((lunarInfo[iYear - 1900] & 0x10000) != 0)
                return 30;
            else
                return 29;
        } else
            return 0;
    }

    /**
     * 传回农历 y年闰哪个月 1-12 , 没闰传回 0
     * @param iYear
     * @return
     */
    private int leapMonth(int iYear) {
        return (int) (lunarInfo[iYear - 1900] & 0xf);
    }

    /**
     * 传回农历 y年m月的总天数
     * @param iYear
     * @param iMonth
     * @return
     */
    private int monthDays(int iYear, int iMonth) {
        if ((lunarInfo[iYear - 1900] & (0x10000 >> iMonth)) == 0)
            return 29;
        else
            return 30;
    }

    public String GreToLun(Calendar cal){
        int leapMonth = 0;
        Date baseDate = null;
        boolean bLeap = false; //判断闰月
        try {
            baseDate = chineseDateFormat.parse("19000131");
        } catch (ParseException e) {
            e.printStackTrace(); //To change body of catch statement use Options | File Templates.
        }
        //求出和1900年1月31日相差的天数
        int offset = (int) ((cal.getTime().getTime() - baseDate.getTime()) / 86400000L);
        // 用offset减去每农历年的天数
        // 计算当天是农历第几天
        //i最终结果是农历的年份
        //offset是当年的第几天
        int iYear, iDaysOfYear = 0;
        for (iYear = 1900; iYear < 2050 && offset > 0; iYear++) {
            iDaysOfYear = yearDays(iYear);
            offset -= iDaysOfYear;
        }
        if (offset < 0) {
            offset += iDaysOfYear;
            iYear--;
        }
        leapMonth = leapMonth(iYear); //闰哪个月,1-12
        bLeap = false;
        //用当年的天数offset,逐个减去每月（农历）的天数，求出当天是本月的第几天
        int iMonth, daysOfMonth = 0;
        for (iMonth = 1; iMonth < 13 && offset > 0; iMonth++) {
            //闰月
            if (leapMonth > 0 && iMonth == (leapMonth + 1) && !bLeap) {
                --iMonth;
                bLeap = true;
                daysOfMonth = leapDays(iYear);
            } else
                daysOfMonth = monthDays(iYear, iMonth);
            offset -= daysOfMonth;
            //解除闰月
            if (bLeap && iMonth == (leapMonth + 1)) bLeap = false;
        }
        //offset为0时，并且刚才计算的月份是闰月，要校正
        if (offset == 0 && leapMonth > 0 && iMonth == leapMonth + 1) {
            if (bLeap) {
                bLeap = false;
            } else {
                bLeap = true;
                --iMonth;
            }
        }
        //offset小于0时，也要校正
        if (offset < 0) {
            offset += daysOfMonth;
            --iMonth;
        }

        String sMonth = "";
        if (iMonth > 9){
            sMonth = String.valueOf(iMonth);
        }else {
            sMonth = "0" + String.valueOf(iMonth);
        }

        return String.valueOf(iYear) + sMonth + String.valueOf(offset + 1);
    }


}
